Variable camshaft phaser

Abstract

A camshaft has a front part forming a journal part for a wheel of a timing pulley (a drive member). A stub shaft (a driven member) is secured to the front of the camshaft and disposed within a cylindrical body of the timing pulley. An annular slide is disposed and coacts with the cylindrical body and the stub shaft for phasing action. The magnitude of axial movement of the slide determines the magnitude of relative rotation between the timing pulley and stub shaft. Fixedly attached to a timing pulley cover is a body formed with a cylindrical bore receiving a piston and a valve bore receiving a spool of a valve for regulating supply of fluid to and discharge thereof from a pressure chamber defined by the piston in the cylindrical bore. A motor is fixedly attached to the timing pulley cover is coupled with a worm of a worm gearing including a worm gear. A motion connection between the piston and the slide is established by a piston rod, a push rod, a cross bar and a slide spring biasing the slide. A lever has one end abutting on an actuator pin for a spool of the valve and the opposite end pivoted to the worm gear. The lever is operatively coupled with the piston rod. The lever provides a position feedback of the piston rod to the valve.

What is claimed is: 
     
       1. A variable camshaft phaser comprising: coaxial drive and driven members;   coupling means including a slide disposed between said drive and driven members for permitting relative rotational movement between said drive and driven members in response to axial movement of said slide such that the magnitude of relative rotational movement between said drive and driven members is determined by the magnitude of axial movement of said slide;   an electro-hydraulic actuator including a body formed with a cylindrical bore disposed outside of said drive and driven members, a piston slidably received in said cylindrical bore and defining in said cylindrical bore a pressure chamber, and a piston rod fixed to said piston, said cylindrical bore and defining in said cylindrical bore a pressure chamber, and a piston rod fixed to said piston, said piston being movable between two limit positions thereof;   a push rod supported by said driver member and having one end abutting on said piston rod and an opposite end;   a cross bar having one and opposite end portions abutting on said slide and a center portion receiving said opposite end of said push rod;   a slide spring acting on said slide in such a direction as to provide motion connection between said piston rod, said push rod, said cross bar, and said slide,   wherein said electro-hydraulic actuator includes valve means for regulating supply of fluid to and discharge thereof from said pressure chamber, a worm gearing including a worm and a worm gear, a motor coupled with said worm for turning said worm, and a lever pivotally supported by said worm gear, said lever being so operatively connected to said position feedback of said piston rod to said valve means.   
     
     
       2. A variable camshaft phaser as claimed in claim 1, wherein said valve means include a spool, an actuator pin and a valve spring biasing said spool and said actuator pin to keep said actuator pin in abutting contact with said lever. 
     
     
       3. A variable camshaft phaser as claimed in claim 2, wherein said lever has one end portion abutting on said actuator pin and an opposite end portion pivotally supported by said worm gear. 
     
     
       4. A variable camshaft phaser as claimed in claim 3, wherein said lever is formed with a window through which said piston rod extends. 
     
     
       5. A variable camshaft phaser as claimed in claim 4, wherein said electro-hydraulic actuator further includes a stop ring fixedly retained by said piston rod. 
     
     
       6. A variable camshaft phaser as claimed in claim 5, wherein said lever has a lobe portion mating with said stop ring. 
     
     
       7. A variable camshaft phaser as claimed in claim 6, wherein said actuator pin of said valve means abuts on said lever to keep said lobe portion in contact with said stop ring. 
     
     
       8. A variable camshaft phaser as claimed in claim 7, wherein said spool of valve means has a supply position and a closed position. 
     
     
       9. A variable camshaft phaser as claimed in claim 8, wherein said valve means is adapted to block supply of fluid to and discharge thereof from said pressure chamber when said spool assumes said closed position thereof and to allow supply of fluid to said pressure chamber but block discharge of fluid from said pressure chamber when said spool assumes said supply position thereof. 
     
     
       10. A variable camshaft phaser as claimed in claim 9, wherein said mechanical means includes a slide spring acting on said slide in such a direction as to bias said piston rod toward said pressure chamber. 
     
     
       11. A variable camshaft phaser as claimed in claim 10, wherein said lever is adapted to push said actuator pin to urge said spool against said valve spring toward said supply position thereof in a transient state when said piston moves away from said pressure chamber. 
     
     
       12. A variable camshaft phaser as claimed in claim 11, wherein said lever is adapted to allow said valve spring to move said spool beyond said closed position thereof in a transient state when said piston moves toward said pressure chamber. 
     
     
       13. A variable camshaft phaser as claimed in claim 2, wherein said actuator pin of said valve means and said worm are displaced around said piston rod through 180 degrees. 
     
     
       14. A variable camshaft phaser as claimed in claim 13, wherein said body is fixedly attached to a timing pulley cover and said motor is fixedly attached to said timing pulley cover. 
     
     
       15. A variable camshaft phaser as claimed in claim 1, wherein said driven member includes a stub shaft formed with a pair of diametrically opposed slots through which said cross bar extends. 
     
     
       16. A variable camshaft phaser as claimed in claim 15, wherein said drive member includes a timing pulley including a wheel and a cylindrical body surrounding said stub shaft and said slide. 
     
     
       17. A variable camshaft phaser as claimed in claim 16, wherein said drive member further includes a cover fixedly retained by said cylindrical body, said cover being formed with a central opening through which said push rod extends. 
     
     
       18. A variable camshaft phaser as claimed in claim 17, wherein said driven member further includes a camshaft to which said stub shaft is fixedly attached.